THE law of the mechanical equivalent of heat may be summed up in the following propositions, viz.:

The heat required in order to raise a given weight of water one centigrade degree of temperature can also lift the same weight 1,300 feet, or, more exactly, 424 metres. Thus to the unit of heat there corresponds a definite amount of work.

Conversely, a given amount of work produces also a definite amount of heat; in other words, there is required an amount of work equal to 1,300 foot-pounds, in order to raise the temperature of one pound of water one centigrade degree.

Heat and motion, therefore, are convertible.

Chemical processes are, in the last resort, the true sources of heat.

Here only a certain portion of the heat reappears in the shape of available mechanical work, the proportion for the steam-engine being one-twentieth of the heat produced by combustion of coal, and in the human body one-sixth of the heat developed by the conversion of the bodily constituents.

Every one knows what a revolution this law has brought about in physics and mechanics: it has added a new chapter to physiology.

There is only one science which, so far, has drawn no advantage from the discovery of the source of force and work, and that is no other than the very science of work, or political economy—in German, Volkswirthschaftslehre.

The grandest discovery in the doctrine of forces is as yet not even mentioned, far less turned to account, in a science whose object, nevertheless, is simply force—work.

But, then, this science is called Wirthschaftslehre. Surely no other name could so ill denote the thing as this, and I confess that I have always had an aversion against calling honest work by such a name. Wirthschaftslehre suggests ideas as remote as possible from economy—taverns and tavern-keeping. Far better is the Anglo-French term of political economy. If we must have a German name for the idea, let it be simply Arbeitswissenschaft—the science of work—for political economy, from first to last, has to do with nothing but human labor and its relations.[1]

But if we call this science no longer Volkswirthschaft, or political economy, but the science of labor, the very name will clearly show that it can rest on no other basis save the law of energy, of motion—the great law of the mechanical equivalent of heat. For work, including human work, is motion, and motion is heat. Of course, political economy does not touch on the laws of nutrition, the laws of food substances or their transformation, for that is the province of chemistry and physiology. Political economy has to do only with the value of work, its price, and thence explains the phenomena of the market. Labor is the natural process whose social relations are known as political economy. The fundamental idea which political economy derives from labor is that of value. The production, the consumption, and the exchange of values (Werthschaffung, Werthverbrauch, Werthtausch), are the three principal divisions of the science of political economy.

In science there is no question that the value of a thing must express only the human labor expended on it. Price is the sum of the values that are given in order to move the will of the owner to renouncement of his right in the thing, his possession and his enjoyment of the work embodied in the thing. The idea of value requires determination of a value unit, for only thus can we know the value; or, to speak more exactly, only thus can we conceive the labor expended on the thing. We must be able to say, not only that labor has been expended on the thing, but also how much.

Marx was the first to essay the determination of a value-unit. This he found in a fixed term of "labor-time," usefully expended in the work. But time is no measure. The measure must be a thing, if it is to be cognizable at all, and such a measure is presented to us only in Mayer's law.

For, if work be equal to motion, and motion to heat, then a given amount of work (task) can also be regarded as equal to the amount of materials expended in producing the heat required for such work (motion). And hence, just as we compare a given net amount of effect from a steam-engine with the coal expended, so may we compare a certain amount of work with the amount of food expended in producing it; and since wheat contains all the essential elements of nutrition, we may compare a task with the quantity of wheat expended in performing it. Where a day's wages is paid in the shape of a day's provisions we have a crude example of the application of this theory.

Hence, as natural forces are gratuitous, the value of a thing expresses the amount of food expended in its production; and the value-unit is a fixed quantity of this food, say so much as is won by a day's work.

Exchange of values is effected with the aid of a thing in which are expressed the food-units required for its production; this is metal coin. Hence exchange-metal is both value and an index of value.

Mayer's law furthermore gives the law of wages. The workman must get back what he has expended in his labor in the shape of food; and this expenditure must be supposed to cover the cost of his bringing up and development, as also provision against old age when he can no longer work.

The idea of capital, too, and especially of the justification (Berechtigung) of capital, falls under Mayer's law. Experience teaches that the amount of food-material gained by labor is in excess of that expended in labor. This excess is capital in the strict sense, perfectly justified capital.

In virtue of the law of equal wages for equal work, every one, even though he does not produce (if we may so speak) food-stuffs, is entitled to the same surplus in recompense (food-stuffs) that he would have earned by work expended in the production of food-stuffs.

Perhaps it will be objected that Mayer's law applies to bodily labor, not to mental; but here, too, it holds good. The natural forces are gratuitous: it is only human labor that produces value. Now to natural forces belong not only the materials of the animal, vegetable, and mineral kingdoms, but also intellectual qualities, even genius itself.

Genius is a natural force which possesses a value only in so far as work has been expended in developing and applying it; this work produces values by consuming values.

All mental labor is at the same time brain-labor. The brain consumes a certain amount of food-material. Of course, all the other involuntary bodily movements which go on simultaneously with the brain-movements, as also the necessary periods of rest, must be taken into account in estimating the value of the products of mental labor.

↑For the benefit of the reader who is not acquainted with German, it may be well to explain that in that language the ordinary meaning of the word Wirth is host, innkeeper; and of Wirthschaft, innkeeping, tavern, public-house.